Conventionally, art for estimating position and posture of articulated object estimate three-dimensional position and posture of an articulated object, for example, a human object, in an image obtained from a monocular camera, its accumulated video, or the like. The art for estimating position and posture of articulated object are used for human behavior analysis and suspicious individual detection in a monitoring field, avatar motion synthesis for a virtual reality world, a remote control interface of a machine, or the like. One example of the conventional art for estimating position and posture of articulated object is disclosed by Yoshinari KAMEDA, Michihiko MINOH, Katsuo IKEDA in “A Pose Estimation Method for an Articulated Object from its Silhouette Image” (The Transactions of the Institute of Electronics, Information and Communication Engineers D-II. Vol. J79-D-II, No. 1, January 1996, pp. 26-35.).
The art for estimating position and posture of articulated object disclosed in “A Pose Estimation Method for an Articulated Object from its Silhouette Image” is art for estimating three-dimensional position and posture for a two-dimensional image of a human body (multi-articulated object) obtained from a monocular camera, and has the following elements and operations. A human body silhouette image is obtained for the input image obtained from the monocular camera. The position and posture of a human body (multi-articulated object) model which reflects an accurate shape of the estimation target is manipulated to obtain a human body silhouette image of the model. The position and posture of the model is searched when the both human body silhouette images match with each other. The three-dimensional position and posture of the human body (multi-articulated object) in the input image are obtained from the three-dimensional position and posture of the model after matched. In the search processing, sub search processing for each portion is performed by using a tree structure of the human body (multi-articulated object) model, thereby throughput for the search is reduced more than in a method in which search processing is performed simultaneously for all the portions.
As for the art for estimating position and posture of articulated object disclosed in “A Pose Estimation Method for an Articulated Object from its Silhouette Image”, the number of combinations of parameters for manipulating the articulated object model is very large, which results in very large calculation costs in model fitting for estimating the position and posture of the articulated object. Since, it is intended to estimate every postures of the articulated object.
To adapt the conventional art for estimating position and posture of articulated object to real time processing faces some problems to be solved.
Other art related to the art for estimating position and posture of articulated object includes the followings.
Japanese Laid Open Patent Application (JP-A-Heisei, 7-302341) discloses a posture detection device for detecting the posture of a human body by using genetic algorithms.
Japanese Laid Open Patent Application (JP-P 2002-63567A) discloses an object position and posture estimation device for estimating the position and posture of a target object by using color data on the surface of the target object.
Japanese Laid Open Patent Application (JP-P 2003-109015A) discloses a body movement measurement method for estimating a change in the posture of a hidden body portion from a change in the posture of a measurable body portion by using subordinate relation between variables indicating the postures.
Japanese Laid Open Patent Application (JP-P 2003-150977A) discloses a system that permits expressing time-series signals of articulate angles of a three-dimensional model with a small number of parameters. This system obtains posture parameters, from a person in a two-dimensional image, of each object constituting the three-dimensional model of a human body. From the posture parameters obtained, independent components of movement are acquired. By utilizing a space of the acquired independent components of movement, a movement of the three-dimensional model is generated. From the generated movement of the three-dimensional model, a two-dimensional dynamic image is generated.
Japanese Laid Open Patent Application (JP-P 2004-213589A) discloses a posture estimation device capable of detecting a posture in a short time without being influenced by the brightness of an input image. This device includes a matching image generation section and a pattern matching section. The matching image generation section binarizes each pixel of the input image of a specific portion, and further specifies a component whose size is within a set range to obtain a binary image. The pattern matching section detects the posture by verifying the binary image with a predetermined template.